JP2022037208A - Biological sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological sensor which is capable of detecting a motion of each muscle and is easy to attach and constitute.

SOLUTION: A biological sensor (100), in use, is mounted on a living body as a subject. The biological sensor includes: a light emitting unit (11) for irradiating a living body with light; a light receiving unit (12) for receiving return light from a muscle of at least a part of the living body; and an output unit (13) for outputting information on the deformation of the muscle of the part on the basis of a detection signal from the light receiving unit corresponding to the received return light.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a biosensor, and more particularly to a technical field of a biosensor that measures a state of a living body using optical technology.

As a device of this type, for example, a device that exerts exerted muscle strength corresponding to the minimum value of oxygen saturation in blood of the subject's muscle estimated from a correlation table showing the correlation between oxygen saturation and exerted muscle strength. It has been proposed (see Patent Document 1).

Alternatively, a device that is fixed to the arm of the subject by a wearing band, has a pushing member that changes according to the contraction state of the muscle, and outputs a detection signal corresponding to the movement displacement of the pushing member has been proposed. (See Patent Document 2).

Japanese Unexamined Patent Publication No. 2001-70289 Japanese Unexamined Patent Publication No. 5-068675

In the technique described in Patent Document 1, since the oxygen saturation that decreases (that is, changes appear) is monitored by muscle contraction for a certain period of time, there is a technical problem that instantaneous muscle contraction cannot be detected. There is a point. In the technique described in Patent Document 2, since the wearing band is wrapped around the arm of the subject, for example, a contraction in which the movement of the agonist muscle and the movement of the antagonist muscle are combined can be detected, and the contraction of each muscle can be detected. There is a technical problem that it cannot be done.

In addition, the electromyogram that measures the potential on the body surface requires time and effort to attach the sensor, and in addition, a technical problem that a highly accurate detection circuit for detecting the weak potential is required. There is.

The present invention has been made in view of the above problems, for example, and an object of the present invention is to provide a biosensor that can detect the movement of individual muscles and is easy to attach and configure.

The biosensor of the present invention is a biosensor attached to a living body as a subject in order to solve the above-mentioned problems, and is a light emitting portion that irradiates the living body with light and at least one part of the living body. A light receiving unit that receives the return light from the muscle of the above, and an output unit that outputs information on the deformation of the muscle of the one part based on the detection signal from the light receiving unit corresponding to the received return light. To prepare for.

The actions and other gains of the present invention will be apparent from the embodiments described below.

It is a block diagram which shows the outline of the biological sensor which concerns on Example. It is a figure for demonstrating the measurement principle of the biological sensor which concerns on Example. This is an example of a biological signal. This is an example of the detection signal before and after filtering. It is an example of the output of the biosensor according to the embodiment. This is an example of measurement results for each of a plurality of muscles. It is a figure which compared the output of the biological sensor which concerns on an Example, and the output of an electromyogram.

An embodiment of the biosensor of the present invention will be described.

The biological sensor according to the embodiment is a biological sensor attached to a living body as a subject, and receives light from a light emitting portion that irradiates the living body and a muscle of at least one part of the living body. A light receiving unit is provided, and an output unit that outputs information regarding deformation of a muscle in one portion based on a detection signal from the light receiving unit in response to the received return light.

The biosensor is attached to the living body at the time of its use. Here, the biological sensor may be attached to the living body by, for example, a dedicated wearing member such as a band, or may be attached to the living body by, for example, medical paper tape or the like.

The light emitting unit emits light having a wavelength of, for example, 660 μm to 940 μm (red light to infrared light). The wavelength of the light emitted from the light emitting unit is not limited to the above wavelength, and may be appropriately set according to, for example, the measurement target. The light receiving unit receives the return light from the muscle of at least one part of the living body.

For example, an output unit including a memory, a processor, or the like outputs information on the deformation of the muscle of one part based on the detection signal from the light receiving unit.

Specifically, when a muscle in one part contracts, the physical distance between the light emitting part and the light receiving part decreases and the muscle pressure increases as compared with the case where the muscle is stretched (when relaxed). .. As a result, when the muscle in one part contracts, the amount of return light received by the light receiving portion increases (that is, the signal level of the detection signal increases) as compared with the time when the muscle is stretched.

Therefore, the output unit outputs, for example, information indicating the signal level of the detection signal as information regarding the deformation of the muscle of one part.

According to the biological sensor according to the present embodiment, since information on the deformation of the muscle is output based on the return light from the muscle of one part, it is possible to detect a momentary change of the muscle of one part. Is. In addition, since the light receiving unit receives the most return light from the muscle closest to the biosensor (here, the muscle of one part), the detection signal from the light receiving unit is the closest to the biosensor. The effects of muscle deformation are dominant. That is, according to the biosensor, only the deformation of the muscle of one part can be detected.

Further, since the biosensor optically detects the deformation of the muscle, the configuration can be simplified and the handling can be facilitated as compared with the electromyogram that measures the weak potential of the body surface. can.

In one aspect of the biosensor according to the present embodiment, the output unit determines that the increase in the signal level of the detection signal is the contraction of the muscle in one part.

According to this aspect, it is possible to detect the deformation of the muscle of one part relatively easily, which is very advantageous in practical use.

In another aspect of the biosensor according to this embodiment, the light emitting part and the light receiving part are arranged on a flexible member.

According to this aspect, since the distance between the light emitting portion and the light receiving portion on the member can be kept constant, the measurement result by the biosensor can be reproducible and the biosensor can be easily applied to the living body. Can be attached to.

In another aspect of the biosensor according to the present embodiment, an attenuation means for attenuating a signal component having a period longer than a predetermined period included in the detection signal is further provided.

It has been found by the research of the inventor of the present application that the detection signal includes the influence of a physiological reaction such as a change in cardiac output. The influence of the physiological response contained in the detection signal (that is, the component related to the physiological response of the signal) is longer than the fluctuation cycle of the detection signal due to the change in muscle.

Therefore, in the present embodiment, the attenuation means attenuates the signal component having a period longer than the predetermined period included in the detection signal. Therefore, according to this aspect, the deformation of the muscle of one part can be suitably detected.

An embodiment of the biosensor of the present invention will be described with reference to the drawings. In the following examples, it is assumed that the subject is pedaling the bicycle.

The configuration of the biosensor according to the embodiment will be described with reference to FIG. FIG. 1 is a block diagram showing an outline of a biological sensor according to an embodiment.

In FIG. 1A, the biological sensor 100 includes a light emitting unit 11, a light receiving unit 12, a calculation unit 13, and a display unit 14.

The light emitting unit 11 has a light emitting element such as an LED (Light Emitting Diode). The wavelength of the light emitted from the light emitting unit 11 may be appropriately set according to, for example, the measurement target.

The light receiving unit 12 has a light receiving element such as a PD (Photodioe). The light emitting unit 12 receives at least the return light from the muscle of the living body as a subject to be measured. Here, "return light" typically means light scattered or reflected by a living body. The light receiving unit 12 outputs a biological signal as a "detection signal corresponding to the received return light" according to the present invention.

As shown in FIG. 1B, the calculation unit 13 includes a bandpass filter 131 and a normalization unit 132. The details of the operation of the calculation unit 13 will be described later.

Here, the measurement principle of the biosensor 100 will be described with reference to FIG. FIG. 2 is a diagram for explaining the measurement principle of the biological sensor according to the embodiment.

In FIG. 2, first, each of the light emitting unit 11 and the light receiving unit 12 of the biological sensor 100 is attached to a portion including a muscle to be measured of a subject. Each of the light emitting unit 11 and the light receiving unit 12 does not have to be attached directly to the skin of the subject or via a gel or cream, and the movement of the muscle to be measured, such as clothes in close contact with the skin, appears. If it is such clothes, it may be worn over the clothes.

As shown in FIG. 2A, it is desirable that each of the light emitting unit 11 and the light receiving unit 12 is arranged on a flexible member (note that in FIG. 2B, the flexible member is shown for convenience of explanation. Not shown). However, each of the light emitting unit 11 and the light receiving unit 12 does not have to be arranged on the flexible member. The "flexible member" according to the embodiment is an example of the "flexible member" according to the present invention.

Now, when the muscle contracts, the myosin filament pulls the actin filament to the center of close proximity, and the myosin filament and the actin filament overlap each other deeply, so that the muscle fibers are dense and the whole muscle is rounded compared to the relaxed state of the muscle. It changes to a shape (see FIG. 2 (b)).

When the muscle contracts, as shown in FIG. 2, the light emitting unit 11 and the light receiving unit 12 approach each other, and the angle formed by the normal of the light emitting surface of the light emitting unit 11 and the normal of the light receiving surface of the light receiving unit 12 changes. (In FIG. 2, it changes from "θ ₁ " to "θ ₂ "). As a result, the optical distance from the light emitting unit 11 to the light receiving unit 12 is shortened. Therefore, among the light emitted from the light emitting unit 11 and scattered or reflected by the muscle to be measured, the amount of light incident on the light receiving unit 12 increases.

In addition, when the muscle contracts, the intramuscular pressure increases and the blood flow to the active muscle is restricted, so that the amount of light absorbed by the blood is reduced as compared with the time when the muscle is relaxed. Therefore, when the muscle contracts, the amount of light scattered or reflected by the muscle to be measured increases.

That is, the amount of light detected by the light receiving unit 12 (that is, the signal level of the output biological signal) has a correlation with the change in the muscle to be measured.

When the subject is pedaling the bicycle, the leg muscles of the subject periodically contract and relax. When the biological sensor 100 is attached to the leg of the subject, the biological signal output from the light receiving unit 12 has a period synchronized with pedaling, for example, as shown in FIG.

By the way, the biological signal includes the influence of a physiological reaction such as a change in cardiac output. Specifically, as shown in FIG. 4A, the entire biological signal fluctuates up and down in a relatively long cycle due to the physiological reaction. The biological signal shown in FIG. 4 shows fluctuations over about 10 minutes.

Therefore, in this embodiment, the bandpass filter 131 (see FIG. 1B) of the calculation unit 13 attenuates the components caused by the physiological reaction contained in the biological signal. As a result, the signal output from the bandpass filter 131 is as shown in FIG. 4B.

The filtered signal output from the bandpass filter 131 is normalized by the normalization unit 132 (see FIG. 1B). Specifically, the normalization unit 132 normalizes the filtered signal by setting the maximum value of the signal amplitude of the filtered signal as the maximum contraction state of the muscle and the minimum value of the signal amplitude as the non-contracted state of the muscle.

Subsequently, in the normalization unit 132, for example, the maximum value of the signal after normalization is set to 100% of the contraction rate of the muscle, and the minimum value of the signal after the normalization is set to 0% of the contraction rate of the muscle. Outputs information indicating time fluctuations. The "information indicating the time variation of the contraction rate of the muscle" according to the embodiment is an example of the "information regarding the deformation of the muscle at one site" according to the present invention.

In this embodiment, the crank angle of the bicycle on which the subject is pedaling is detected by the crank angle sensor 20 (for example, a pedaling monitor). The display unit 14 of the biosensor 100 uses the crank angle detected by the crank angle sensor 20, and corresponds, for example, with the information indicating the time variation of the muscle contraction rate output from the calculation unit 13 and the crank angle. Attached and displayed (see Fig. 5).

If displayed in this way, the subject or the like can know the transition of the muscle contraction rate during pedaling, which is very advantageous in practical use.

Further, the biological sensor 100 is not limited to the pair of light emitting units 11 and the light receiving unit 12, and may include a plurality of pairs of light emitting units and light receiving units. With this configuration, for example, the straight thigh muscle (anterior thigh), bicep muscle (outside the hamstrings), gluteal muscle (ass), and half tendon-like muscle (inside the hamstrings) used for pedaling motion of a bicycle. ), The transition of the contraction rate of each of a plurality of muscles such as the anterior tibial muscle (anterior calf) and the gastrocnemius muscle (posterior calf) (see FIG. 6).

As a result, for example, it is possible to evaluate the proper use of muscles during pedaling, detect unintended eccentric contractions (extensible muscle contractions), and the like, which is extremely advantageous in practical use.

(Effect of this example)
The most practical technique that can evaluate the motion state of muscles is an electromyogram. Therefore, the measurement result of the biological sensor 100 according to this embodiment and the measurement result by the electromyogram are compared with reference to FIG. 7. The graphs shown in FIG. 7 show fluctuations in the muscle contraction rate for one cycle (that is, for a crank angle of 360 degrees).

Although the explanation of the principle of the EMG is omitted, the EMG detects the action potential caused by the command to contract the muscle from the brain. On the other hand, the biological sensor 100 optically detects changes in muscles as described above. In other words, the biosensor 100 detects the result of muscle changes. As described above, the electromyogram and the biosensor 100 have different measurement principles, but as shown in FIG. 7, the measurement results for each muscle have very high similarity.

Therefore, it can be said that the measurement result by the biosensor 100 is appropriate and has the same measurement accuracy as the electromyogram. That is, the biosensor 100 can measure momentary changes in muscles for each muscle with high accuracy, similar to an electromyogram.

However, since the electromyogram measures the action potential of the muscle, it is possible to measure the muscle contraction that does not accompany the deformation of the muscle, for example, isometric contraction. On the other hand, since the biological sensor 100 measures the muscle contraction from the change in the amount of light received due to the change in the muscle, the muscle contraction without the deformation of the muscle cannot be measured.

Here, in particular, if the biosensor 100 can physically fix the light emitting unit 11 and the light receiving unit 12 to a portion including the muscle to be measured, the change in the muscle can be measured, and the handling thereof is very easy. be. In addition, since the biosensor 100 only needs to be able to detect a signal at a speed (for example, 10 Hz or less) at which the subject operates, for example, the circuit configuration and the like can be simplified and miniaturized. Therefore, the biosensor 100 can suitably measure the state of the muscle in a field such as a sports field in which the muscle is actively moved.

In this embodiment, pedaling of a bicycle is taken as an example, but if it is a relatively simple periodic motion such as jogging or running, the biosensor 100 may measure as shown in FIGS. 5 to 7. The results can be displayed.

The "calculation unit 13" and the "bandpass filter 131" according to the embodiment are examples of the "output unit" and the "attenuation means" according to the present invention, respectively.

The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the claims and within the scope not contrary to the gist or idea of the invention that can be read from the entire specification, and the biosensor accompanied by such modification is also possible. It is included in the technical scope of the present invention.

11 ... light emitting unit, 12 ... light receiving unit, 13 ... arithmetic unit, 14 ... display unit, 20 ... crank angle sensor, 100 ... biosensor, 131 ... bandpass filter, 132 ... normalization unit

Claims (1)

A biosensor attached to a living body as a subject,
A light emitting part that irradiates the living body with light,
A light receiving portion that receives return light from at least one part of the living body, and a light receiving portion.
An output unit that outputs information regarding the deformation of the muscle of the one site based on the detection signal from the light receiving unit in response to the received return light.
A biosensor characterized by comprising.

Images